This is the blog for Yale's undergrad course ANTH204:
An introduction to the patterns and processes of human genetic variation. Topics include: human origins and migration; molecular adaptations to environment, lifestyle and disease; ancient and forensic DNA analyses; and genealogical reconstructions.

Wednesday, October 5, 2011

It is a commonly held belief that humans have stopped evolving. Thanks to superior technology and the developed world’s plentiful supply of food and shelter, many scientists believed natural selection to no longer have an impact of humans. A recent study by a team of researchers from University of Quebec at Montreal proves otherwise. Led by Emmanuel Milot and DenisReale, the team studied remarkably throughout data on births, marriages, and deaths collected by a catholic church in a small island town on the St. Lawrence River near Quebec. The data revealed that over 140 years, 1799-1940, the average age of women when they gave birth to their first child fell from 26years to 22years. Additionally, they had an average of 4 more children due to this earlier beginning of their reproductive life. This drastic change in such a brief time span (relative to human history) not only provides convincing evidence that humans are still evolving but it may be occurring at perhaps an increasing speed. Alternative explanations for this phenomenon, such as cultural trends or environmental influences, have been offered however they have been rejected by the research team as each would logically lead to other observable changes in the population (ex: had increased healthcare been the cause, increased infant mortality should have followed suit, which it did not). Though cultural and environmental factors may still have some influence, the majority of this change can be attributed to biological evolution. Additionally, the trait in question (age of women when giving birth to their first child) has previously been proven to be highly heritable. This, in addition to the strong homogeneity of the society, lack of drastic wealth and lifestyle disparity, and a strong pattern of inbreeding, created good conditions for a prominent change in genetics. The result- “the most recent known instance of human evolution in response to natural selection.” (Wade, NY Times)